1. Field of the Invention
The present invention relates to a vibrating gyroscope, and more particularly to a vibrating gyroscope used in a video camera or the like to detect external vibrations such as hand shaking by detecting a rotational angular velocity and cancel out the vibrations on the basis of the detected information.
2. Description of the Related Art
One type of vibrating gyroscope is disclosed in Japanese Laid-open Patent Publication No. 8-278145, which is described below with reference to FIG. 1. As shown in FIG. 1, the vibrating gyroscope 1 comprises a vibrator 2 made of a rectangular shaped piezoelectric ceramic material, and two support members 3 having a circular columnar shape and being made of silicone-based resin material.
The vibrator 2 is fixed to a substrate 4 via the support members 3 in such a manner that one end face of each support member 3 is connected to a respective one of two nodes N which occur when the vibrator 2 vibrates and the other end face of each support member 2 is connected to the base plate 4.
Japanese Laid-open Patent Publication No. 8-278145 further discloses that the support members 3 are also formed into a rectangular shape instead of the circular columnar shape.
The vibrating gyroscope according to the conventional technique has the following problems.
In the conventional vibrating gyroscope in which the vibrator is supported on the support members in the form of columns, the diameter of the columns should be large enough to stably support the vibrator. However, the large diameter of the columns can cause the vibration of the vibrator to leak to the substrate through the support members. As a result, a reduction occurs in the amplitude of the vibration of the vibrator. The magnitude of a signal detected by the vibrating gyroscope varies in proportion to the amplitude of the vibrator, and thus the magnitude of the detected signal decreases with the reduction in the amplitude of the vibration of the vibrator. Therefore, the vibrating gyroscope of such a type has a rather low sensitivity.
It is therefore an object of the present invention to solve the above problems. More specifically, it is an object of the present invention to provide a vibrating gyroscope in which a vibrator is supported in a stable fashion without causing a significant reduction in the sensitivity thereby achieving a high sensitivity.
According to a preferred embodiment of the present invention, a vibrating gyroscope comprises a vibrator having at least one node, and a support member having a thin flexible portion and an expanded portion which is connected the thin flexible portion and has a larger area than the thin flexible portion. The expanded portion of the support member is fixed to the vibrator at the at least one node.
The expanded portion may have a through-hole therein.
According to another embodiment of the present invention, a vibrating gyroscope comprises a vibrator having at least a first node, and first and second support members supporting the vibrator such that the first and second support members sandwich the at least first node of the vibrator.
The vibrator in either embodiment may comprise first and second piezoelectric substrates stacked with each other and being polarized in opposite directions of their thickness directions; first and second split electrodes formed on a principal surface of the first piezoelectric substrate; and a common electrode formed on a principal surface of the second piezoelectric substrate.
The vibrating gyroscope may further comprise third and fourth support members, and the vibrator may have a second node. The third and fourth support members support the vibrator such that the third and fourth support members sandwich the second node of the vibrator. Each of the first, second third and fourth support members may have a thin flexible portion and an expanded portion which is connected to the thin flexible portion and has a larger area than the thin flexible portion, and each of the first, second third and fourth support members may be fixed to the vibrator at the expanded portion thereof.
One of the first and second support members may be electrically connected to the first split electrode and one of the third and fourth support members may be electrically connected to the second split electrode.
According to the vibrating gyroscope of the preferred embodiment of the invention, the contact area between the vibrator and the support members is large enough so that the vibrator is firmly supported by the support members thus achieving high resistance to shock. Other than the connecting portion, the support member is thin and flexible so that the support member has little influence on the vibration of the vibrator, thus not preventing the free vibration of the vibrator and thereby ensuring that the vibrator vibrates with a large enough amplitude to provide a large output signal so that the vibrating gyroscope has a high sensitivity.
Further, the vibrator is supported by being vertically clamped in a sandwich fashion by support members; hence, a problem in which the portions where the vibrator and the support members are bonded are damaged when the vibrator oscillates and the vibrator eventually detaches and falls will not arise, enabling the support structure to provide improved impact resistance and stable joint states.
Moreover, since the support members hold the vibrator therebetween, the support members are not particularly required to have any substantial height, so that the support structure may be made shorter, permitting the entire apparatus to be made shorter accordingly.
For the purpose of illustrating the invention, there is shown in the drawings several forms which are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.